openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 90 insertions, 0 deletions

diff --git a/include/uapi/rdma/mana-abi.h b/include/uapi/rdma/mana-abi.h
new file mode 100644
index 000000000..a75bf32b8
--- /dev/null
+++ b/include/uapi/rdma/mana-abi.h
@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: (GPL-2.0 WITH Linux-syscall-note) */
+/*
+ * Copyright (c) 2022, Microsoft Corporation. All rights reserved.
+ */
+
+#ifndef MANA_ABI_USER_H
+#define MANA_ABI_USER_H
+
+#include <linux/types.h>
+#include <rdma/ib_user_ioctl_verbs.h>
+
+/*
+ * Increment this value if any changes that break userspace ABI
+ * compatibility are made.
+ */
+
+#define MANA_IB_UVERBS_ABI_VERSION 1
+
+enum mana_ib_create_cq_flags {
+	/* Reserved for backward compatibility. Legacy
+	 * kernel versions use it to create CQs in RNIC
+	 */
+	MANA_IB_CREATE_RNIC_CQ	= 1 << 0,
+};
+
+struct mana_ib_create_cq {
+	__aligned_u64 buf_addr;
+	__u16	flags;
+	__u16	reserved0;
+	__u32	reserved1;
+};
+
+struct mana_ib_create_cq_resp {
+	__u32 cqid;
+	__u32 reserved;
+};
+
+struct mana_ib_create_qp {
+	__aligned_u64 sq_buf_addr;
+	__u32 sq_buf_size;
+	__u32 port;
+};
+
+struct mana_ib_create_qp_resp {
+	__u32 sqid;
+	__u32 cqid;
+	__u32 tx_vp_offset;
+	__u32 reserved;
+};
+
+struct mana_ib_create_rc_qp {
+	__aligned_u64 queue_buf[4];
+	__u32 queue_size[4];
+};
+
+struct mana_ib_create_rc_qp_resp {
+	__u32 queue_id[4];
+};
+
+struct mana_ib_create_wq {
+	__aligned_u64 wq_buf_addr;
+	__u32 wq_buf_size;
+	__u32 reserved;
+};
+
+/* RX Hash function flags */
+enum mana_ib_rx_hash_function_flags {
+	MANA_IB_RX_HASH_FUNC_TOEPLITZ = 1 << 0,
+};
+
+struct mana_ib_create_qp_rss {
+	__aligned_u64 rx_hash_fields_mask;
+	__u8 rx_hash_function;
+	__u8 reserved[7];
+	__u32 rx_hash_key_len;
+	__u8 rx_hash_key[40];
+	__u32 port;
+};
+
+struct rss_resp_entry {
+	__u32 cqid;
+	__u32 wqid;
+};
+
+struct mana_ib_create_qp_rss_resp {
+	__aligned_u64 num_entries;
+	struct rss_resp_entry entries[64];
+};
+
+#endif